stop/dispose/cancel a Task C#

i am trying to deploy DLLs inside a windows service by importing DLLs from various repositories like google drive/ dropbox/ ftp etc...

But before any new DLL can be instantiated, I would want the previous running instance to be shut down.

I am using tasks and reflection in this.

I am unable to figure out how to cancel the task that instantiate the DLL at run time ( as the instantiated dll is a long running application example file watcher.. )

    CancellationTokenSource cts = new CancellationTokenSource();
    CancellationToken ct = cts.Token;

            // instantiate the dll though reflection
        t = Task.Factory.StartNew(() =>
        {
            try
            {
                Assembly assembly = Assembly.LoadFile(Directory.GetCurrentDirectory() + @"\" + dllName);
                Type type = assembly.GetType("myclass.Program");

                MethodInfo minfo = type.GetMethod("Main", BindingFlags.Public | BindingFlags.NonPublic |
                          BindingFlags.Static | BindingFlags.Instance);
                minfo.Invoke(Activator.CreateInstance(type), null);

            }
            catch (Exception ex)
            {

                log.Error(ex.ToString());
            }
        }, cts.Token);

Ques : I want to cancel the task t before my appication detects a new dll and tries to execute that through this task code.